03 July 2019

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Radiopacity of luting cements: decrease after aging?

Lara Figini

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Longevity of the prosthetic restoration  is important and depend on several factors, such as the type and degree of adaptation of the prosthetic restoration, previous preparation of the tooth, and the type of cement used.
The selection of cement should be guided by the complexity of each case and by the physical and biological properties of the materials. The radiopacity of luting cements is  very important in radiographic diagnosis and follow-up, because it allows differentiation between cements, dental structures, and secondary carious lesions. Crucial is keep over time the correct radiopacity of the luting cements.     

MATERIALS AND METHODS
An in vitro study, published in the Journal of Prosthodontic in December 2018, the authors evaluated the radiopacity of various luting cements submitted to different aging procedures. The authors prepared twenty discs (1 × 4 mm) for each of the following prosthetic luting cements: Zinc phosphate, RelyX Luting 2, Variolink 2, AllCem, RelyX U200, Multilink, Panavia F2.0 e RelyX ARC.
The specimens were then randomly divided into two groups (n = 10 / group), according to the aging procedure used:

group A: in which the samples were submitted to thermocycling;
group B: in which the samples were kept in water. 

Before and after aging procedures, samples were subjected to radiographic examination. Radiopacity was assessed by optical density, which was measured using ImageJ software. The values ​​were converted to aluminum millimeters with a logistic regression calibration curve. The data were analyzed by means of ANOVA and post-hoc Tukey tests (α = 0.05).   

RESULTS
In the group A  RelyX Luting 2, RelyX U200 and PanaviaF2.0 showed a statistically significant reduction in radiopacity (p <0.05).
In the control group B all  cements showed a significant reduction of radiopacity (p <0.05), and RelyX Luting 2 and Panavia F2.0 performed below the desired ISO 4049 standard.     

CONCLUSIONS
From the data of this in vitro study, which must however be confirmed by other in vitro and similar clinical studies, it can be concluded that the radiopacity of luting cements decreases after aging, especially after 1 year water storage.           

CLINICAL IMPLICATIONS
The clinician should hold in consideration the loss of radiopacity for luting cements during  follow-ups, for the differentiation between cement, dental structures and secondary carious lesions. 

For additional informations: 
Evaluation of Radiopacity of Luting Cements Submitted to Different Aging Procedures.